the_debt_of_time

"Miss Granger, you are already facing suspension from this school. You, Potter, and
Weasley are out-of-bounds, in the company of a convicted murderer and a werewolf. For
once in your life, hold your tongue!"
She tried again, "But if... if there was a mistake―"
"Keep quiet, you stupid girl!" Snape shouted, looking suddenly quite deranged.
"Don't talk about what you don't understand!"
Sirius growled loudly and, despite the wand against his neck, he advanced toward
Snape with a murderous expression. "You watch your fucking―" he began to say, but was
cut off by a loud shout of, "Expelliarmus!"
Snape flew backward into the wall, and Sirius and Remus both turned back to see
Harry standing there with his wand aimed high.
"Thank you, Harry," Sirius said with a proud grin.
Hermione was shaking, brown eyes wide. "You attacked a teacher!"
"I'm still not saying I believe you," Harry told Remus.
Remus nodded as he approached Snape to check his pulse, wincing at the blood on
the man's head. That's not going to be easily forgotten, he thought to himself while retrieving the
collected wands, handing one back to Sirius.
"I understand, Harry. I suppose it's time we offered you some proof." He looked
to Sirius, hoping that his friend had something to show.
Almost immediately, Sirius stuck his hand into a pocket and removed a folded piece
of paper, handing it out.
"The idiot Minister tossed that at me when he came for inspections. Taunting me
about Harry's birthday," Sirius said with a frown. "I knew the rat immediately. How many
bloody times had I seen him transform? The caption said that the kids would be going back
to Hogwarts. I had to.. ." He looked up, his eyes meeting Harry's. "I had to make sure
you were safe."
"Merlin," Remus whispered, staring at the photograph in the paper. "His front
paw."
"What about it?" Ron said defiantly.
"He's got a toe missing," Sirius answered.
"Of course," Remus said on a breath. "So simple, so brilliant. He cut it off himself?"